Researchers from the US space agency have successfully used balloons to detect earthquakes in the California desert.
The experiment tested whether similar balloons could be sent to Venus to study the planet seismic activity. NASA recently announced plans to launch two future missions to Venus.
NASA scientists were fortunate enough to perform the test in July 2019, when a series of powerful earthquakes hit the area around Ridgecrest, California. The main earthquake occurred on July 4 and had a magnitude of 6.4, according to the United States Geological Survey reported in May. Several other large earthquakes struck the area within days and more than 10,000 aftershocks were reported over the next six weeks.
The experiment involved four large solar balloons designed to fly at altitudes of 18 to 24 kilometers. The team attached instruments to balloons that measure changes in atmospheric pressure. The equipment is used to detect sound waves rising from below the surface during earthquakes and aftershocks.
Researchers say that by studying the seismic wave activity of a rocky planet, like Earth, they can learn more about how that planet developed and its current state.
Venus is also a rocky planet. It is our closest neighbor in the solar system and the second closest planet to the sun. Its structure is similar to that of Earth, but a little smaller. But unlike Earth, Venus has an extremely hot surface temperature and a very dense atmosphere. Such conditions make it difficult for spacecraft to survive in Venus’ atmosphere or on its surface.
Scientists have long thought about the possibility of studying seismic activity on Venus. They want to know more about how the planet developed such extreme conditions.
Researchers at NASA’s Jet Propulsion Laboratory (JPL) believe they can send balloons like those tested in California during a mission to Venus. The experiment – which also involved scientists from the California Institute of Technology (Caltech) – was recently described in a study in Geophysical research letters.
Scientists at JPL and Caltech have been developing their balloon-based method since 2016. But strong seismic activity in the California desert in July 2019 gave them a good opportunity to test their equipment in the field.
The seismic energy of earthquakes is transmitted in the atmosphere and produces sound waves. These waves are detected by seismic stations on the ground. But the JPL team reported that it was able to detect, for the first time, earthquake-related seismic activity from its balloons.
One of the balloons detected seismic sound waves seconds after a 4.2 magnitude aftershock was confirmed by detection stations on the ground. At the time, the balloon was about 3 miles above Earth.
Researchers hope the balloons will allow further studies of seismic activity on Venus to provide information about the planet interior. For example, they say this method could help them understand why the surface of Venus stays hot enough to melt lead. It can also lead to discoveries of liquids, such as water or oil, on the planet.
Jennifer M. Jackson is a professor of mineral physics at the Caltech Seismic Laboratory who helped lead the research. It said in a press release that much of our understanding of the Earth’s interior comes from studying the seismic activity that takes place deep inside the planet. The method could also be possible with Venus.
“Observations of seismic activity… would strengthen our understanding of rocky planets. But the extreme environment of Venus forces us to investigate novel detection technical. “
The researchers say they plan to continue flying balloons over active seismic areas to improve their ability to identify seismic events over large areas from the air. They also plan to add more instruments and fly more balloons at the same time. This could allow them to identify where earthquakes are occurring without needing confirmation from ground stations.
I am Bryan Lynn.
Bryan Lynn wrote this story for VOA Learning English, based on reports from NASA, Geophysical Research Letters, and the US Geological Survey. Mario Ritter, Jr was the editor.
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Words in this story
detect – v. discover or notice something
seismic – adj. related to or caused by an earthquake
mission – m. a flight performed by an aircraft or spacecraft to perform a specific task
transmit – v. send signals
interior – m. the inner part of something
novel – adj. new or different from anything else
technical – m. a particular or special way of doing something